Recovery of precious metal from desert sands and from desert placer



Dec. 16,1941.

A. K. ANDREWS RECOVERY OF PRECIOUS METAL FROM DESERT SANDS AND FROM DESERT PLACER Filed Jan. 21, 1939 2 Sheets-Sheet l I I5 I" 7 I as Z I INVENTOR Mbert K Andrews BY ATT Dec. 16, 1941. K ANDREWS I 2,265,977

RECOVERY OF PRECIOUS METAL FROM DESERT SANDS AND FROM DESERT PLACER Filed'Jan. 21, 1959 2 Sheets-Sheet 2 H I u i 27 HYVENTOR Albert K. Andrews ATTO EY Patented Dec. 16, 1941 REGOVERY F PRECIOUS METAL FROM DESERT PLACER,

SANDS AND. FROM. DESER'D Alb'ertK'. Andrews, Vancouver; -Wash.- Application January 21, 1939,,Seri'alNo. 252,142

(01: zen-44 10 Claims.

My invention relates to a machine:- fori-therecovery. of precious 'metal from desert :sands and from: desert placer bearing mate-riali The primary purpose and r obj ect ofv inventionis: to ,provide a. machine; that Willi effect the recovery of theprecious"- metal;v from; dry placer in which the recovery, is: efiectediw-ithoutthe-.use of water. The recovery being efiectedthrough' the use 'of' airseparation caused by the "circulating; of: air: of relatively high velocity through the: treating machines.

The invention :is comprised zprimari-lyofi a shell: made up of 1 a. plurality of; independent: sections that may; he secured; together by flanges: disposed upon the-midesections of the; shell. A feeding hcppenis superposed theshelliand:power means: isprovided for delivering screenemmata rial; into the: hopper; The'hopperrisidisposed-2 at: the tonal the shell and theelievatcd material, flows 4 from thehopper: throu h the? action; of: gravity into the treatingrsh'elh pluralitm-of treating heads are disposed within the shell and" in, spaced relation; witheachiother: with a. recoveryhead and* a, screen beingdisposed in the" top end"of:each;ofithe;heads; Nleansciszprovi'dew through theside wall .of 'the shell fort'thezremoving: of each: of; the heads independently; Khopeper is immediately disposed below: each: of? the heads and the: screens permit. aretreating of .the: material inzthe sheadzdisposed; immediateiy'theree' below.

Independent means is' provided forzradinitting. treating air; into each of the-treating'heads and; below the recovery head'in.order'thatfthe airiwill: flow;up.wardithrough each of: thetreating: heads;

This device provides :for a-smultiplextreatmentz of the material as ittflows throughthe sheetibyz the action from the feeding hopper to the base of the shell. Dross material'is delivered through oil-bearing conveyor. Power: means is-providedfor eliminating the dust developing: within-f the shell through the action of a suction creating exhauster. The dust finally-being deliverediinto a dust collector.

The primary objectcof "my invention is for. the recovery of precious metalsfromdesertfsands and desert placer..

A further-object is-to provide a. machinefor: the recovery oi metal concentrate from desert placer without the use oiwater.

A- further object of 'mylinventionsisto providea' machine that'is relatively cheapiinl production and one that will handlea volume ofmaterial. and thus make available a machine for thetreat the base'of'thexshell and isdeposited-.uponran ing-:- offdesertsands and iplacer. materialrthat twill: be relatively, cheap; inifirst cost. One; that will-i have alargesoapacity andlone that isparticularly' adapted :for therecovery of: microscopic randzzfinei: material; of high specific: gravity; fromx desert: sands anddesert materials;

With theseand. incidental ObjBCliSfiIl: View; the invention consists in. certain: novel features-10f: construction; and: combinationr of parts; the: es..-'-- sontial elements; of": which are; set: fortht. in a the; appended? claims; a and: a1- preferredriform; of; ermbodiment of which is: hereinafter-shown; with. reference to the -.drawings;whichaccompany-rand form. a: part: of; this specification;

In the; drawings:

Fig. I is awfragmentary partially sectional Lside view. of anassembled: device:

Fig.2 II 'is: a fragmentary randspartial zangle secational 3 side view:-- of: the; edvice" taken: at a ninety: degree? angle from thetpartial sectional t side-view illustrated: in: Fig: I.

FigzIIIaisfla fragmentary sectional end vievwof theismechanism illustrated in Fig: II. TliiS=viewds-:; taken; on: lines 3:31-0f Fig: .I tlookingc irr. the diree tioniindicatedi Bike" reference; characters;- refer to like parts throughout the-.severakvie'ws;

I provide a;shell:intwhichzthetreatmenttofithematerial: is: to primarily occur; This shell is:

' composed of a base I that has flanges 2- and '3 disposed upon: its oppositely: disposed ends=with thei base: end of the shell? uniformly tapering downward'rto form a-restricted opening tthrougltwhich the residue ofithountreated material will flow. A discharging chute 5 terminatesthelower end or the base} of the shell and an" olfldearing conveyor operates ir'nrnediately below the discharge end ofthe spout; The; discharge end of f the spout is 'cutatan angle as-illustratedj at'l to shape the end so that it willibe disposed substantially parallelito the. ofif-bearing conveyor;

An endless bucket. line is, run withinltlieoconveyer frame and a plurality oflspacedlliucketss 8., outwardly extend. therefrom and the buckets are positioned to. receive materials discharged;- throughthespout.

Intermediate she1l-members-9 and ID are superposed the base I and each citric-intermediate: shell members; have flanges: disposedqat their opposite ends to facilitate. their beingsecured t0;- gether andrto thebase end; I. andvthe headill. The head; of the shell ll is preferably: crowned and. the flanges 1 12; are: disposed upon-i thein'base: GI'IdItOi adaptfthe same. for-being secured to andi attached to the uppermost one of the intermediate shell members 9.

A loading hopper I3 is disposed central of the head II and a pipe I4 extends through the head I I and discharges material into the shell.

A loading ladder I5 leads from the stock-pile and the upper end of the ladder is fixedly secured through the use of suitable brackets I5 to the feeding hopper I3. A loading bucket is provided for delivering material to be treated into the hopper I3. A plurality of treating heads here shown as four in number are disposed within the shell. Each of the treating heads have a common center line and this center line is also common to that of the pipe I4 in order that the material to be treated will flow in an orderly manner through the device. Each of the heads is composed of a cone-stepped head I8 made of wool felt or other suitable material to permit air under velocity to pass therethrough. The treating head I 8 is mounted upon a suitable support and the head is made up of a plurality of steps I9 that form riifiesfor the recovery and maintaining of the heavy'placer material that lodges thereupon. The head is removable and replaceable in order that cleanup maybe made from the head.

A screen that is inclined downwardly is disposed at the base of the treating head I8. The

screen is preferably made of sections as illustrated at 2I, 22, 23 and 24 in Fig, Each of the sections is hinged to permit'a jig-like action being imparted thereto. Each of the screen sections has a rim 25 disposed about its outer periphery. A pair of lugs 26 are secured to the rim and a jig bar 21 is hingedly secured to the lugs 26. The jig bars 21 are vertically disposed within the shell and a power driven cam-shaft 28 is disposed transversely of the'base end of the shell with a pulley 29 being mounted upon the shaft that is adapted for being driven with a belt 38 trained therearound. A belt 38 is power actuated from a source of power not here shown. The shaft 21 moves within a suitable guide 3 I. With the guide being supported by an arm 32 that is secured and its base end 33 that is secured to the shell I. A cam 34 is mounted upon the shaft 28 and the same engages the bottom end of the rod and imparts an up and down movement thereto as the shaft is rotated upon which the cam 34 is mounted.

v The larger material is screened out between the hoppers and the screened out material is eliminated therefrom through the base I and is deposited upon the off-bearing conveyer 5. The material passing through the screen 20 flows into thehopper 35 and a discharge pipe 36 forms the discharge end of the hopper 35 and deposits that fine material upon the head 31 that is disposed therebelow. The heads 31, 38, and 39 are made similar to, in general construction, to that of the head I8. The details of construction may vary somewhat due to the fact that progressively finer material is to be treated within the succeeding heads disposed therebelow.

Screens 48, 4|, and 42 are similar to the screen 28 and these screens are associated with each of the respective heads 31, 38, and 39 and each of the-heads and each of the screens are independently removable.

' Hoppers 43, 44, and 45 are also associated with the respective heads 31, 38, and 39.

. Air chests 46, 41, and 48, and 49 are associated with each of the hoppers 35, 43, 44, and 45 and treating air is admitted into each of the chests 45,41, 48, and 49 through air delivery tubes 50 and 5I that are associated with each side of the assembly. Air is supplied to the respective tubes 58 and 5I through a feeder pipe 52 into which air is pumped from any suitable pressure blower 53. Each of the tube chests 58 and 5I are in communication with the respective chests 46, 41, 48, and 49 by suitable piping connections. In order that the volume and velocity of air being admitted into the respective chests may be settable and determinable, I provide suitable valves in each of the pipes as illustrated at 52, 53, 54,

55, 56, 51, 58, and 59. These valves permit a fine adjustment in the fiow of the air from the respective pipes 58 and 5| into the respective chests 46, 41, 48, and 49 so that the pressure and velocity, or volume of air that is to flow through the treating heads 31, 38, and 39 may be manually controlled.

All of the material passing through th respective screens is retreated in the head disposed immediately therebelow and the degree of fineness of material to be recovered is somewhat determinable with the help of the treating head material and the velocity of the air flowing therethrough. All material not passing through the respective screens 'gravitates into the base of the shell and is removed therefrom through the use of the bucket line.

In order that the dust collecting within the shell may be continuously removed therefrom and be prevented from entering the open atmosphere, I provide one or more suction chests 6| with a plurality of suction tubes 62 communicating the chest with the interior of the shell.

A syphon head 63 is disposed at one end of the chest BI and a fluid under pressure is supplied to the syphon head with a pipe 64 that leads to a source of supply of the fluid, as air or steam. The dust sucked from the shell fiows through a suitable tube 65 to a dust collector 66. The dust collector 66 is supported upon a suitable sup- P rt 61. r

The size and character of the shell structure will be determined by the character of the maair flotation is easily made, the head II may be directly secured to the base I, and but a single recovery head with its associated parts may be used. If additional recovery problems are encountered,.one or more of the intermediate members 9 and I0 is used. In order that the heads I8, 31, 38, and 39 may each be removed from the shell, I provide a door 68 within the respective shell members with the door 68 being positioned substantially opposite to that of the head to be removed,.in order that'the head assembly may be taken directly through the respective door members.

It will also be noted that the delivery tubes 5| have a plurality of joints 69 disposed therein, in order that the delivery tube may be fitted to the respective lengths of the shell that is to be used. It will also be noted that the delivery tubes 5I are, here shown, to be connected upon their lower ends to the Y 10 disposed upon the inner end of the feeder pipe 52 and suitable joints '1I connect the respective ends of the Y with the delivery tubes 5I. The velocity and volume of the air to be supplied to the respective chests 48, 41, 48, and 49 is determined by the character of the material to be treated, the specific gravity of the same and the fineness of the material is also somewhat determined by the fineness of the recovered,

While the form of mechanism herein shown and described is admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to confine the invention to the embodiment herein shown and described, as it is susceptible of embodiment in various forms, all coming within the scope of the claims which follow.

What I claim is: a

1. In a device of the class described, thecombination of a shell, a treating head disposed within the shell, said treating head having a porous body made of a felt material, and said treating head being arranged in stepped conical formation and a screen disposed at a lower elevation than that of the treating head outwardly extending therefrom and a hopper disposed immediately therebelow, means for imparting a jigging motion to the head and screen and means for supplying a controlled volume and velocity of air into the hopper and means for exhausting the shell.

2. In a device of the class described, the combination of a shell base, a plurality of shell sections removably securable to each other and to the base, a top for said shell, a material hopper disposed central of the shell and superposed the top, means for conveying materials into the superposed hopper, a plurality of treating heads disposed within the shell, said treating heads being disposed one above the other and in axial alignment with each other and each disposed axially of the shell, each of said treating heads having a central wool fabric top that is formed of concentric riifles and a metal screen disposed peripherally of the fabric top, and disposed at a lower elevation than the wool fabric, the top of the fabric end of the screen being downwardly sloping, a hopper disposed immediately below each of the heads, an air chest disposed immediately below each of the fabric tops of each of the heads, means for supplying air in controlled volume to each of the riflied fabric tops, means for imparting a jigging action to each of the fabric heads and screens disposed adjacent therearound, means for exhausting the shell of dust laden air and means for off-bearing dross material from the base of the shell.

3. In a device of the class described, the combination of a structural shell, said shell having a convex top and a concave bottom, means for delivering material to be treated through the top and for eliminating dross material through the bottom of the shell, means for creating a negative atmospheric pressure within the shell, a plurality of treating heads disposed in vertical spaced relation with each other, each of said treating heads formed of a central part made of a riflled wool fabric, a metal screen ring disposed about the central part and outwardly and downwardly extending from the central part, means for forcing air in predetermined velocity and intensity to blow articles above a predetermined specific gravity from the central part, and means for imparting an up and down motion to the central part of each head.

4. In a device of the class described, in combination, a shell, means for delivering materials through the top of the shell, a plurality of spaced treating heads disposed axially of the shell and in spaced vertical relation, screening means disposed at the side of and surrounding each of the treating heads for screening materials being deposited thereupon and flowing thereupon, the central part of each of the heads being rifiled and made of a wool fabric material to permit air under pressure and velocity passing therethrough in sufficient intensity to prevent articles oflow specific gravity coming in contact with thecentral part of the treating head, means for imparting an up and down motion to that part of the treating head through'which the air freely passes, and means for creating a negative atmospher c pressure within the shell. I 5

5. In a device of the class described, in combination, a cylindrical shell with the longitudinal axis of the shell being disposed vertically, a plurality of treating heads that are coaxial with the shell and with each other disposed in vertical spaced relation within the shell, means for removing each of the treating heads through the side of the shell, means for passing air under pressure and in volume independently through the central part of each of the treating heads, with the central part of each treating head being riffied, means for removing dust particles from the air before such passage through the treating heads, means for exhausting dust laden air from the shell, means for collecting the dust from the air so exhausted, and means for screening the mass to be treated as it passes from one treating head before its entry upon the treating head disposed therebelow.

6. In a device of the class described, in combination, a shell, treating heads formed of concentric rings of felt riflles arranged in stepped formation disposed within the shell, in spaced relation with each other and one above the other, means for imparting an up and a down motion to the rifiled parts of each of the treating heads, with the central part of each of the treating heads being sufficiently porous to permit the free passage of air under pressure and velocity therethrough and of sufficient density to support material of a high specific gravity deposited thereupon and means for feeding materials continuously into the shell and for off-bearing dross materials through the base of the shell and means for clarifying the air being passed upward through the felt covered heads.

'7. In a device of the class described in combination, a fabricated shell means for feeding material into the one end of the shell and for off-bearing dross material from the other end of the shell, a plurality of treating heads disposed within the shell, and positioned to receive deposited fed material entering the shell and for flowing downward therethrough, said treating heads being covered with felt material that is formed of a plurality of rings in stepped formation and means for imparting a jigging action to the heads, means for supplying a predetermined volume and velocity of clarified air below each of the treating heads, and means for forcing the air through riffled felts, means for exhausting the shell, and for removing the top from the shell.

8. In combination in a treating head for the recovery of the precious metal concentrates from desert placer, comprising a recovery head the top surface of which is made of wool felt, said top surface of the felt being arranged in a series of concentric riflles, means for jigging the wool felt recovery head, a classifying screen disposed below and surrounding the riffled wool felt, and so arranged that material that is not retained on the wool felt will be required to flow over the screen, means for causing an air blast to flow through the riffled felt, means for continuously feeding materials to the top surface of the head, a chamber for said head and means for'exhausting said chamber.

9. In combination in a device for treating desert placer, comprising a shell, a plurality of spaced treating heads disposedwithin the shell with the treating heads having a top surface that is circular, that is formed of wool feltarranged in rifiles and having a screen disposed around the head and positioned to receive dross material flowing from the head and classifying screens disposed around the treating head, means for blowing air upward through said heads, means for removing the dust from said air before the 10. In combination in a device of the class described, comprising a shell, a plurality of treating heads disposed within the shell, and said heads being spaced apart and above the other, said treating heads being made up of a frame and a riflled filter of such porosity as to permit an air blast being blown upward therethrough yet of suflicient density to collect and support materials of high specific gravity thereupon that are deposited thereupon, means for jigging the riffled filter, means for eliminating dust from the air that is to be blown through the filter before entering the filter, means for feeding materials into the air blast above the filter, said screen being positioned to permit dross material from the filter passing thereover.

ALBERT K. ANDREWS. 

